"Smell through the sound" may mean that incense (usually used to express worship or prayer) can convey people's wishes or information. "Communication" here can be understood as "conveying information" or "conveying information".
There may be some misunderstanding about yawning, because yawning is usually not understood as an act that can "connect the sky". This sentence may be a metaphor or a symbol to describe a certain state or situation. One possible explanation is that yawning may represent a state of drowsiness or exhaustion, and "falling into the sky" may imply the depth or influence of this state. Therefore, "yawning in the sky" may describe a state of extreme drowsiness or exhaustion.
However, due to the lack of context and context, the above explanation may not be completely accurate. The specific meaning of this sentence may require more background information to be accurately interpreted.